The X-Men are in the middle of their latest training session. Marvel Girl is given the task of opening a locked box using her telekinetic powers. Once it is opened she finds a birthday cake stashed inside. Professor Xavier explains that it has been one year since classes first started at the school, and he felt that the date should be celebrated.

Meanwhile four other mutants (Toad, Mastermind, Quicksilver and the Scarlet Witch) are seen having dinner. Mastermind tries to impress the Scarlet Witch, but she is not interested in him. Mastermind threatens her but Quicksilver intervenes to protect his sister. Magneto is elsewhere seen stealing a freighter and returning it to his secret headquarters somewhere in the Atlantic Ocean. When Magneto returns Toad informs him that Quicksilver and Mastermind were fighting. Quicksilver and the Scarlet Witch tell Magneto that they do not want to be members of his group anymore, but Magneto informs them that they are forever in his debt. The group has a flashback to a town in Europe where Magneto saves the Scarlet Witch from an angry mob that wants to kill her for burning down a barn with her mutant powers.

Magneto and his Brotherhood of Evil Mutants use the stolen freighter to attack the small nation of San Marco in South America. Professor Xavier learns of the attack when he reads the newspaper and tries to contact Magneto using his telepathic powers. Professor Xavier and Magneto dispute their different views on mutant and human relations; Professor Xavier believes that they should coexist with one another while Magneto believes that homo-superior should rule the world. Mastermind creates an imaginary army to frighten San Marco's populace so that the Brotherhood of Evil Mutants can easily take over the country.

Professor Xavier and the X-Men travel to San Marco using the story of an American professor and his students on a goodwill mission. Once they are in the country the X-Men change into their costumes and attack the Brotherhood. Mastermind tries to scare the X-Men away by creating an illusion of a fire wall in the X-Men's path. Professor Xavier realizes that the fire is not real, so he enters it to show his students that there is nothing to be afraid of.

The X-Men then devise a plan to attack the Brotherhood, but do not realize that the door to the palace has been booby trapped with a bomb. Just before Beast opens the door, Professor Xavier senses the danger and hurls himself in front of the X-Men to protect them. The Brotherhood escape from the palace, but not until after Quicksilver disarms a second bomb intended to destroy the entire nation along with the X-Men. Professor Xavier regains consciousness only to learn that his telepathic powers were damaged during the explosion.

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